Manhattan Project

The Manhattan Project is the name of the program that developed the atomic bomb in the 1940s. The United States dropped two atomic bombs on Japan in 1945 to end World War II (1939–45). Ever since then, the world has wrestled with the problem of how to prevent a nuclear war.

Nuclear potential

The atomic bomb is a military weapon based on the science of splitting the nuclei within certain elements. (The nucleus is the center of an atom, the smallest part of a chemical element.) The splitting process is called nuclear fission, and the elements that are used in the process are uranium and plutonium.

Nuclear fission was discovered by scientists in Germany in late 1938. Physicists throughout the world quickly recognized the possibility of using the enormous energy released in this reaction to build weapons. There were, however, many questions to answer about the new science and challenges to overcome before a bomb could be built.

Both Germany and England investigated the possibility of a nuclear weapon early in World War II, but the war quickly demanded their full attention. Only the United States had sufficient resources and the scientific manpower to undertake the project at the time.

The development of a nuclear weapon

The United States was fearful that Germany, led by Nazi dictator Adolf Hitler (1889–1945), might develop an atomic bomb. President Franklin D. Roosevelt (1882–1945; served 1933–45) initiated secret research to produce the first weapon. The project became known as the Manhattan Project.

In 1939, funding was increased to allow theoretical and experimental research to move more quickly. In 1942, the Office of Scientific Research and Development began overseeing feasibility studies in laboratories. By mid-1942, it was obvious that new factories would have to be built. Congress approved a special fund for the president to use for secret projects, and in December 1942 Roosevelt approved $400 million for the project. By the end of the war, funding for the project totaled an enormous and unforeseen $2 billion.

With such immense funding and pressure to produce a weapon to use during the war, General Leslie Groves (1896–1970), who was in charge of the project, initiated research in as many areas as possible at the same time. No approach was to be disregarded until proven unsatisfactory. In December 1942, physicist Enrico Fermi (1901–1954) succeeded in producing and controlling a chain reaction of fission in a reactor built at the University of Chicago.

To support further research, top-secret plants were constructed. A plutonium-generating reactor was built in Hanford, Washington . A gas-diffusion facility was built in Oak Ridge, Tennessee , and a physics research lab was constructed in Los Alamos, New Mexico .

Scientists at Los Alamos worked to overcome the technical problem of how to amass fissionable material and shape it into a bomb. Uranium and a newly created element, plutonium, were at the center of the research. Eventually, two types of bombs were developed at Los Alamos. The first bomb was tested successfully in a southern New Mexican desert at Alamogordo on July 16, 1945. The explosion shook the earth with the power of twenty thousand tons of dynamite, and it was the beginning of the atomic age.

The end of World War II

By summer 1945, Germany and Italy had surrendered to the United States and its Allies . Japan, however, was not willing to surrender, despite aggressive attacks from the United States. President Harry S. Truman (1884–1972; served 1945–53), after issuing several warnings and demands for surrender, gave orders to use the atomic bomb as a military weapon.

On August 6, 1945, the bomber Enola Gay dropped a uranium bomb on Hiroshima, Japan. It totally destroyed four square miles of the city and killed more than fifty thousand people. Then on August 9, 1945, a bomber approached Japan. This time it headed for the city of Nagasaki and dropped a plutonium bomb. It destroyed one-third of the city and killed more than forty thousand people. The Japanese surrendered days later.